Stamping dies are cut to exact shape but rough finish using numerically controlled machining. A machining cutter with a "ball nose" is used to create the rough surface, which has a scalloped or grooved appearance after cutting. The bottoms of the grooves are at the desired final surface level, so the scallops must be removed. At present this is done manually and takes a long time. When the die is almost completely finished, slight residues of the groove bottoms may still be seen.
Alternate "automatic" methods exist. One of these involves another type of numerically controlled machining, using a flat nose cutter which is "nutated" as it spins. The result is a surface that has a segmented flat appearance as if it had been finished by a spatula. Some additional finishing is still required. However, there is no reference indicating where the final desired surface lies. A person grinding such a die does not know when to stop; he can make the surface smooth but cannot tell when it is at the correct level. For this reason, the nutating cutter method is not widely used.
Another existing "automatic" method is a type of machine called a die polisher. Such a machine works on dies machined by ball-nose cutters and uses a small cutting disk to smooth local regions of the die. Polishing of each region is done by manually recording a series of points. The machine moves the polishing head in a fixed pattern through the series of taught points a fixed number of times or until the human operator stops it. It performs no measurements and cannot determine when it has finished the die to the desired shape. The cutting disks are small and require that the original grooves be small and close together, requiring in turn increased machining time prior to polishing. Such a machine also requires manual teaching and manual attention.